ELEMENTARY EXPERIMENTAL PHYSIOLOGY 45 



the level of the drum, and mark under each upstroke the weight 

 used, calculated as directly applied to the muscle. 



Make a diagram, showing and comparing the work done with 

 each weight. 



FIG. 41. The effect of temperature upon the contraction of the gastrocnemius 



muscle. 



The'Wme is marked in ^ s second. The tracing should be read from right to left. Figures on 

 curve are the temperatures of the salt solution. (Pembrey and Phillips.) 



3. Effect of Varying the Temperature. 



METHOD. After recording a normal twitch, swing the lever off 

 the drum by the base-piece, and cool down the muscle by putting 



FIG. 42. Heights of contraction of a muscle with different strengths of stimuli. 



M marks the make and B. the break of the primary circuit. The numbers refer to the distances 



in cms. of the secondary from the primary coil. (A.P.B.) 



ice round it, separating the ice from the muscle by a piece of blotting 

 paper saturated with normal saline. After 2 or 3 minutes remove 

 the ice and paper and swing the lever on to the previous abscissal 

 line, raising or lowering the drum if this is necessary, and when the 



